The for statement is used repeatedly to execute a single statement or a block of statements, as long as the given condition is TRUE.
How for loop works
- The initialization statement is executed only once, at the beginning.
- Then the test condition is evaluated, if the condition happens to be false, the for loop is terminated.
- If the condition happens to be true, control reaches inside the loop, and statements are executed and at the same time update expression is updated.
- Again, the test expression is evaluated.
This process goes on until the test expression is false.
Simple example:
1) To print “hello world” 10 times
#include <stdio.h>
int main()
{
for (int i = 0; i < 10; i++)
{
printf("\n Hello world");
}
return 0;
}
2) To print a table of 2
#include <stdio.h>
int main()
{
int i = 2;
for (; i <22; i+=2)
{
printf("\n %d", i);
}
return 0;
}
In this example, we can see that the variable “i” has been initialized outside the loop.
3) To print 1 to 10
In this the updated expression is missing, which can be given even later.
#include <stdio.h>
int main()
{
for (int i = 1; i <=10;)
{
printf("\n %d", i);
i++;
}
return 0;
}
4)In this we can see multiple initialization and update expression
#include <stdio.h>
int main()
{
for (int i = 1, j=1; i <= 10, j < 10; i++, j+=2)
{
printf("\n i value is : %d and j value is: %d", i,j);
}
return 0;
}
5)This example illustrates Infinite for loop
#include<stdio.h>
int main()
{
int i =1;
for(;;)
{
printf("\n Hello World");
if ( i==10) {
break;
}
i++;
}
return 0;
}
6)Nested For loop
#include<stdio.h>
int main()
{
int i, j;
for(j=1; j<=5; j++)
{
for (i=1; i<=j; i++)
printf ("%5d", i);
printf ("\n\n");
}
return 0;
}
OUTPUT: 1
1 2 1 2 3 1 2 3 4 1 2 3 4 5
Note:
Do not give a semicolon(;) at the end of for loop, there will be no Compilation error but the control will not enter the loop. It is very similar to the body-less loop.
Relevant Posts:
Categories: C Language
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